A connection structure of electronic components which obtains high reliability, by reliably establishing electrical connection of the electronic components is disclosed in Patent Literature 1. As shown in FIG. 14, in this connection structure of the electronic components, a pair of bus bars 501, 503 are assembled to a housing, and a semiconductor light emitting element (LED) 505, which is a light source, is also assembled to the housing. The bus bars 501, 503 in a shape of a bifurcated flat plate have a wire connecting part 507, a Zener diode connecting part 509, a resistor connecting part 511, and an LED connecting part 513. In the resistor connecting part 511, pressure-contacting blades 515, 515 are respectively provided on the bus bars 501, 503 which are bifurcated. In the Zener diode connecting part 509, a single pressure-contacting blade 517 is provided on one of the bus bars 501, and a single pressure-contacting blade 519 is provided on the other bus bar 503.
A Zener diode 521 is connected to a pair of the bus bars 501, 503 in parallel therewith, at a downstream side of a resistor 527, in such a manner that one of lead parts 523 is electrically connected to the one bus bar 501, while the other lead part 525 is electrically connected to the other bus bar 503. When a large voltage is inputted to a circuit by static electricity in a direction where a normal electromotive force flows to the diode, the diode 521 protects the LED from breakdown by the large voltage. In a direction where a counter electromotive force flows to the diode, the diode 521 blocks electrical connection, and thus, protects the LED from the breakdown in the same manner.